Apparatus for turning workpieces

ABSTRACT

Disclosed here are methods and automatic apparatus for grinding cylindrical workpieces, such as the contoured rolls used in metal rolling mills. The methods and apparatus involve (1) automatic finding of the lengthwise center of rolls of different and undetermined lengths so as to establish a reference position for the execution of a numerically programmed path defined relative to the center of a roll as a point of symmetry, (2) the storage of the successive instructions of multi-axis movements making up a numerically defined profile or contoured path, and the use of those instructions repeatedly and in whole or in part as called for by different ones of a sequence of commands read from storage and executed in succession, (3) the automatic alignment of the roll axis parallel to the longitudinal axis of motion in a grinding machine by pivoting of one end of the roll about the other until the sensed difference in positions of the roll surface, along an axis transverse to the longitudinal axis and at locations near opposite ends of the roll, is changed to a predetermined fraction of the originally sensed difference, (4) the initiation of grinding passes from that end of a roll which is largest in diameter, so as to avoid &#39;&#39;&#39;&#39;digging in&#39;&#39;&#39;&#39; or increasing the depth of wheel bite as the wheel moves lengthwise of the roll, (5) the execution of continuous passes of the grinding wheel with pre-programmed values of feed rate, wheel speed, roll speed, continuous infeed and incremental infeed until a preprogrammed thickness of material has been removed from the roll surface, and (6) the grinding down of a roll until it is reduced to a diameter equal that of a previously ground roll of a matched pair. These functions are all obtained by the calling out and execution of pre-established routines in response to the reading from storage of pre-programmed sequence commands, so that in the disclosed method and apparatus there is an automatic progression from each type of operation to the next, and with the following of numerically defined profile whenever it is required.

United States Patent Clark, Jr.

[4 1 Apr. 4, 1972 I541 APPARATUS FOR TURNING WORKPIECES Stephen C. Clark, Jr., Phoenixville, Pa.

[73] Assignee: The Ingersoll Milling Machine Company,

Rockford, 111.

221 Filed: Jan. 25, 1971 211 Appl.No.: 109,525

[72] lnventor:

Related U.S. Application Data [62] Division of Ser. No. 790,323, Jan. 10, 1969.

[52] U.S.Cl. 51/165 TP,51/49 [5 l] Int. Cl ..B24b 5/04 [58] Field ofSearch 51/49, 165 R, 165 T1, 165.71,

Primary Examiner-Lester M. Swingle An0meyWolfe, Hubbard, Leydig, Voit & Osann, Ltd.

[ 5 7 ABSTRACT Disclosed here are methods and automatic apparatus for grinding cylindrical workpieces, such as the contoured rolls used in metal rolling mills. The methods and apparatus involve l) automatic finding of the lengthwise center of rolls of different and undetermined lengths so as to establish a reference position for the execution of a numerically programmed path defined relative to the center of a roll as a point of symmetry, (2) the storage of the successive instructions of multi-axis movements making up a numerically defined profile or contoured path, and the use of those instructions repeatedly and in whole or in part as called for by different ones of a sequence of commands read from storage and executed in succession, (3) the automatic alignment of the roll axis parallel to the longitudinal axis of motion in a grinding machine by pivoting of one end of the roll about the other until the sensed difi'erence in positions of the roll surface, along an axis transverse to the longitudinal axis and at locations near opposite ends of the roll, is changed to a predetermined fraction of the originally sensed difference, (4) the initiation of grinding passes from that end of a roll which is largest in diameter, so as to avoid digging in" or increasing the depth of wheel bite as the wheel moves lengthwise of the roll, (5) the execution of continuous passes of the grinding wheel with pre-programmed values of feed rate, wheel speed, roll speed, continuous infeed and incremental infeed until a preprogrammed thickness of material has been removed from the roll surface, and (6) the grinding down of a roll until it is reduced to a diameter equal that of a previously ground roll of a matched pair. These functions are all obtained by the calling out and execution of preestablished routines in response to the reading from storage of pre-programmed sequence commands, so that in the disclosed method and apparatus there is an automatic progression from each type of operation to the next, and with the following of numerically defined profile whenever it is required.

8 Claims, 28 Drawing Figures PATENTEDAPR M972 3,653,162

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SHEET 10% 18 I vM AC/DC Z R CONVERTER 2 f DETECTOR Has PSL H19 PSR mwigroTof-kd APPARATUS FOR TURNING WORKPIECES l. Contouring Apparatus l 2. Sequence Command System l2 3. Data Manipulation Apparatus l3 D. Methods and Apparatus for Grinding a Roll l5 l. Setup Procedure l5 2. Location of Lengthwise Center; M6l 17 (a) Movement of the Swivel Base to the Center ofB Axis Travel 17 (b) Setting the Platform 35 to the Center of X Axis Travel 18 (c) Movement of Proximity Switches to Operative P9SitiQrts,,,. l8 (d) Movement ofWheel to Center of Roll. 19 3. Automatic Alignment ofthe Roll Axis. 23 (a) a' PQ @li9E.-;-- 23 (b) Movement to Location of First Gaging Band... 25 (c) Bringing the Wheel into Touching Contact with the Roll 26 td) Grinding Right Gage Band to Predetermined Depth L. 27 (e) Movement of Wheel to Location of Left (inge Band 28 tfi Grinding ofthe Left Gaging Band 29 (g) Rctrnction ofthe Wheel Free ofthe Roll. 29 (h) Sensing the Location ofthe Left Gaging Band on the RearSide ofthc Roll 30 4. Determining Direction of First Grinding Pass;

InitialGrinding t (a) Right End Larger 37 (b) Left End Larger 37 (c) Status of the System Prior to First Grinding Pass 38 (d) First Grinding Pass and Continuous Passing... 39 (i) Case IMaten'al Removal Incomplete 40 (ii) C ase l I Mate ialRemglflComplete 4l 5. Rough Grinding 42 1 6. Finish Grinding 43 1 7. Sensing and Signaling the Roll Diameter 44 8. Cleaning Up the Roll Surface by Sparking Passes 49 9. Polishing Passes 50 E. Grinding a Second Roll to the Same Diamqe A 52 F. An Alternative Embodiment 56 C ROSS-REFERENCE TO A RELATED APPLICATION This application is a division of my copending application Ser. No. 790,323,filed Jan. 10, 1969.

BACKGROUND OF THE INVENTION The present invention relates in general to apparatus for the turning of cylindrical workpieces, and while it will find advantageous use in the operation of lathes, the invention is adapted to be applied with special advantages in the operation of grinding machines for shaping or renewing the shape of rolls such as those employed in metal rolling mills.

In the operation of large installations for the rolling of steel or aluminum into thin sheets or strips for coiling, the high inter-roll pressures and roll speeds result in severe wear of the surfaces of the individual rolls. The wear is often non-uniform, and any roll surface irregularities result in magnified surface imperfections in the sheets or strips. It is common practice to change the rolls in a given mill stand frequently, as often as *once per eight hour shift. When each worn roll is removed from the mill, there is a need to have its surface re-finished or re-ground to nearly perfect smoothness and with the desired cylindrical shape (which may be a convex or concave contour lengthwise of the roll to compensate for roll loading pressure and produce a desired cross sectional shape in the rolled strip). To keep a large mill, and the investment which it represents, operating efficiently, it is desirable to re-grind worn rolls not only quickly so that they may be returned to service, but also with precision.

The increasingly severe shortage of skilled machinists leads to the result that manual control of grinding machines ofiers little prospect of satisfying the current demand for rapid and precise grinding of rolls. One particular difficulty encountered in the operation of a grinding machine under manual control is in accurately grinding the roll to a predetermined final diameter and contour while removing as little material as possible from the roll so as to not unduly shorten the usable life of the roll. The movements of the grinding wheel thus must be controlled precisely and, in addition, care must be taken first to determine the final size and shape to which the roll is to be ground and then to terminate the grinding operation once such size and shape have been reached.

SUMMARY OF THE INVENTION The principal object of the present invention is to provide new and advantageous apparatus for automatically machining cylindrical workpieces to desired sizes and shapes as defined and commanded in advance by programmed data which control the machining operation completely and temiinate the operation when the desired size and shape have been obtained.

A related object of the invention is to provide for the sequential execution of different routines or operations in the overall shaping of a cylindrical workpiece, and wherein one or more routines so executed results in the removal of the desired thickness of material from the workpiece surface by successive passes of a tool to remove successive incremental thicknesses-characterized by the advantages that the number of passes need not be estimated or commanded, and that the mere commanding of the removal of a desired thickness results in the automatic accomplishment of all of the individual operational steps, repeated as many times as may be necessary, to effect such removal.

A more detailed object is to provide new and improved apparatus for producing a signal representative of the diameter of a cylindrical workpiece after each pass of a tool, for comparing the signal thus produced with a signal representative of a commanded final diameter, and, when the two signals do not agree, for automatically advancing the tool a predetermined distance toward the workpiece and subsequently effecting another pass of the tool along the workpiece.

The invention also is characterized by the novel mounting and positioning of a workpiece sensor for detecting the surface of the workpiece and producing the signal representative of the diameter thereof, the sensor being movable longitudinally with and located directly opposite the tool so as to be in position to detect the end of the workpiece after each pass of the tool.

The foregoing summary of the invention and the advantageous objectives achieved thereby will be better understood after consideration of the more detailed description of a specific, exemplary embodiment of the methods and apparatus. And additional advantages will also become apparent as the detailed description proceeds with reference to the accompanying drawings. 

1. In a machine tool for turning a nominally cylindrical workpiece and having a tool movable along a Z axis substantially parallel to the longitudinal axis of the workpiece in the machine and movable along an X axis normal to the Z axis; a probe assembly movable along the Z axis in unison with the tool and including a probe body adjustable along the X axis, a probe extensible relative to the body in a direction parallel to the X axis, and means for producing a signal proportional to the displacement of the probe from a reference position relative to the body; the improvement which comprises in combination means for moving said body until the probe is engaged with the surface of the workpiece and deflected relative to the body until said signal takes on a predetermined first value, means for digitally signaling the magnitude of a thickness to be removed from the workpiece, means responsive to said digital signaling for advancing said body toward the workpiece through a distance equal to said magnitude of thickness so that said signal takes on a second value which differs from the first by an amount proportional to said magnitude, control means responsive to an initiation signal for (a) advancing the tool into the workpiece a predetermined increment at one end of the workpiece surface, (b) passing the tool substantially along the Z axis in contact with the workpiece to the opposite end of the workpiece and then repeating (a) and (b), and means responsive to said signal existing at said first value after any tool pass for terminating the operation of said control means.
 2. The combination set forth in claim 1 further characterized in that said control means includes means for retracting said probe into the body and free of the workpiece prior to each pass and means for releasing said probe for extension into contact with the workpiece after each pass, and wherein said means for terminating is responsive to said signal only when the probe is extended at the end of a pass.
 3. The combination set forth in claim 1 further characterized in that said probe assembly is mounted such that the probe therein is disposed on a line parallel to the X axis and passing through the center of the tool, whereby the probe is disposed opposite one end of the workpiece surface after each pass of the tool.
 4. In a machine for grinding a nominally cylindrical roll and having a grinding wheel movable along a Z axis substantially parallel to the longitudinal axis of a roll in the machine and movable along an X axis normal to the Z axis; a probe Assembly movable along the Z axis in unison with the wheel and including a probe body adjustable along the X axis, a probe extensible relative to the body in a direction parallel to the X axis, and a transducer for producing a signal proportional to the displacement of the probe from a reference position relative to the body; the improvement comprising in combination, power means for moving said body parallel to the X axis, a feedback pulse generator coupled to said body for producing a pulse for each predetermined increment moved by the body, means for controlling said power means to move the body toward the roll to a first position in which probe is engaged with the roll and shifted into the body to make said signal have a first value, a counter, means for presetting said counter to hold and digitally signal a number representing a desired thickness Delta R of material to be removed from the roll, means for controlling said power means to move the body toward the roll which pulses from said generator are fed to and counted down in said counter until the latter holds and digitally signals zero, whereupon said body is moved inwardly from said first position through a distance Delta R to a second position in which said signal has a second value; control means responsive to an initiation signal for (a) advancing the wheel into the roll a predetermined increment at one end of the roll surface, (b) passing the wheel substantially along the Z axis in contact with the roll to the opposite end of the roll surface, and then repeating (a) and (b), and means responsive to said signal for existing at said first value after any pass of the wheel for terminating the operation of said control means.
 5. The combination set forth in claim 4 further characterized in that the center of the wheel and the probe lie along a single line parallel to the X axis.
 6. The combination set forth in claim 4 further characterized in that said first value of said signal is zero.
 7. In a machine tool for turning a nominally cylindrical workpiece, said machine tool having a tool movable along a Z axis substantially parallel to the longitudinal axis of a workpiece therein and movable along an X axis normal to the Z axis, the combination comprising front and rear probe assemblies movable along the Z axis in unison with the tool and having respective front and rear probes extensible from front and rear probe bodies into contact with the front and rear surfaces of the workpiece, each said probe body being movable parallel to the Z axis relative to the roll, and each probe assembly having means for producing a signal proportional to the displacement of its probe from a reference position relative to the probe body, means for bringing said front and rear probe assemblies opposite a predetermined axial location on the workpiece and advancing said bodies inwardly until the front and rear signals take on predetermined first values, means for measuring the inward displacements d1 and d2 of said probe bodies from retracted positions in which the spacing between the two probe tips, with the probes deflected to make the front signals have said first values, is a known distance K, means coupled to and responsive to said measuring means for digitally signaling the numerical value of the workpiece diameter D according to the expression: D K -(d1+d2), means for presetting one of said probe bodies in a direction parallel to the X axis to a first position in which the probe signal takes on a null or reference value, means for presetting said one probe body inwardly parallel to the X axis to a second position in which the probe signal takes on a predetermined second value corresponding to a commanded thickness of material to be removed from the surface of the workpiece, control means for causing said tool to execute continuous cutting passes substantially along the Z axis, with incremental infeed along The X axis at the end of each pass, and means for terminating continuous cutting passes in response to the signal from said one probe assembly reaching a null or reference value at the end of any given pass.
 8. The combination set forth in claim 7, further including means for representing by a first set of digital signals a desired final diameter D1 for a workpiece, means for processing said first set of signals and the digital signals from said means for digitally signaling the diameter D of a workpiece to derive and represent by a second set of digital signals a difference Delta R according to the expression Delta R (D- D1)/2, and means for supplying said second set of digital signals to said means for presetting said one probe body inwardly to a second position, whereby upon termination of the continuous passing by said control means, the diameter of the roll has been reduced to the desired value D1. 